Please Listen to the following TED talk and answer the questions followed.（09分20秒-10分07秒）According to the scientific research， the speaker concludes that（）.

A.CO2， methane， and ice sheetswere feedbacksthat simplified global temperature changecausing these ancient climate oscillations to be huge

B.CO2， methane， and ice sheetswere feedbacksthat amplified global temperature changecausing these ancient climate oscillations to be huge

C.CO2， and methanewere feedbacksthat amplified global temperature changecausing these ancient climate oscillations to be huge，even though the climate change was initiatedby a very weak forcing

D.CO2， methane， and ice sheetswere warning signalsthat amplified global temperature changecausing these ancient climate oscillations to be huge

正确答案：CO2， methane， and ice sheetswere feedbacksthat amplified global temperature changecausing these ancient climate oscillations to be huge